Under the Circumstances
by Lunavere
Summary: After being kidnapped off the street, John wakes up in a locker room. Not only does he find out Jim Moriarty's true identity, he discovers that he is in heat... and the only Alpha in the room is Jim Moriarty himself.


**Author's Note:** This is my original work that you are able to find on my AO3 account. If you see this posted ANYWHERE else, please report it and send me a message. Thank you.

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Groaning, John slowly woke up to find that he was in a foreign place. Grey lockers surrounded him, and he was lying on the floor, leaning against one. It felt like his mind was covered in a fog as he tried to piece everything back together. He had been heading over to Sarah's… a taxi driver pulled over to give him a ride… a gun was pulled… he got knocked out somehow… Going rigid, he sat up straight and assessed his situation. He could smell the chlorine of a pool, and he quickly realised he was in a sports centre. Rubbing his eyes, he looked around to find he was alone. Well, he wasn't about to wait for whoever kidnapped him to return. He sprang to his feet, blood rushing to his head as he did so. Immediately, he realised that he was running a bit warm. Pulling on his jumper, he let out a groan as his cold hands touched his hot skin.

"Oh, dear, you weren't supposed to wake up before we put the bomb on you!" a voice sang out.

John smelled the man – an Alpha, going by how powerful the scent was – before seeing him. It was familiar to him, but it was only after seeing the face of Jim from IT as he stepped into the light that John recognised him. "Jim… Moriarty?" he clarified, shifting his weight from one foot to the other. He hadn't caught a last name on Jim's ID, now that he thought about it. "_You_ are Jim Moriarty?"

"You sound disappointed," Jim noticed, stepping a bit closer. His eyes gleamed mischievously. "Not what you thought I would be? Of course, you probably didn't have an exact image in mind. Just not _this_, am I right?"

John tilted his head to the side as he listened. Everything was spot-on. It reminded him of Sherlock in a way. Only this man was much more dangerous than Sherlock would ever be. "How did you know all that?" he pressed, shifting his weight again.

Grinning, Jim answered, "You're easy to read, Johnny." He took another step closer, and John bit back a moan as the scent became stronger. Fear was mixing with arousal, and he was terrified for his sanity. This man had just had him knocked out for reasons John still didn't know. Suddenly, Jim stopped. His eyes widened with realisation and interest. "Oh… Sherlock never bonded you to him?" he pressed, clearly surprised by the epiphany. Most people were once they figured out that Sherlock and John weren't a bonded pair.

Something about the way Jim said that triggered some awareness in John's mind. It was in that moment that John came to the horrible realisation: his heat was starting. That's why his skin felt hot when the hand, which had been on the cold ground, touched it. And why Jim's scent seemed so strong to him. And why he had shifted those times – he was starting to self-lubricate. Setting his jaw, he murmured, "Sherlock bonded once in his younger days." Victor. John had been so upset when he found out. After all, once an Alpha bonded with an Omega, there was no going back. The bond was for life, even if one of the werewolves died. No matter how much John wanted to be completely Sherlock's, he never would be.

"Ah…" Jim responded thoughtfully. He took another step closer and breathed in deeply. "You're unlike anyone I've ever smelled before…"

"Yeah, I get that a lot," John murmured, subconsciously taking a step closer to Jim. The ache in his arse was beginning to set in. Soon, he would be begging to be touched, even if it was by Jim Moriarty. "Nearly died after being bitten. My scent has never been the same since."

Humming, Jim began to prowl, like a predator stalking his prey. His eyes became hard… possessive. It was then that John realised that Jim was probably without a bond as well. "I've never been around an Omega in heat before. They weren't kidding about the natural impulses." With that, he reached out and caressed John's cheek.

John let out a small whimper as he felt the touch, leaning into it despite himself. He felt the thumb stroke his skin again before he realised what he was doing. Jerking away, he fought desperately to control his biological impulses. This was _Jim Moriarty_. A bomber, a kidnapper, a thief, a forger. But John knew he would be lying to himself if he said that Jim's life – dangerous and thrilling – wasn't a bit of a turn on, too. Even so, he had to keep himself grounded.

"What a loyal soldier you are," Jim cooed, almost mockingly. "I'm sure Sherlock would have been pleased to see you fight it." After taking three steps, he cupped John's face again, causing John to groan and lean forward. His heat was beginning to override his thoughts, and he needed more than such simple touches. "But John Watson, I'm afraid you are _mine_ now."

With that, Jim crashed their lips together in a bruising kiss. John moaned, instinctively pressing his body against Jim's. Just as he felt a small nip to his bottom lip, he felt Jim's other arm snake around his back and lock him there. John compliantly opened his mouth, and Jim wasted no time on claiming what was his. For a brief second, John felt the shock – and just a touch of shame – as he submitted willingly to Jim's wishes. There was no fight as Jim's tongue lunged in and explored every nook and cranny of John's mouth, as if he was memorising and mapping it all out. Suddenly, John's knees buckled, and he broke the kiss in order to let out a yelp.

"I've got you," Jim murmured in his ear, using his weight to counteract the fall. He smirked down at John, his arms tightening ever so slightly. "To the showers."

John got his feet underneath himself enough to help Jim walk him over to the showers. By now, he was wet enough to dampen his pants, and the scent was stronger than before. Jim pressed him against one of the walls, letting it support John, before his hands pulled John's jumper completely off. Panting, John looked up at Jim through half-lidded eyes. His body was begging to be touched – anything that would satisfy his craving for physical attention. Immediately, John tried to rebuke himself in order to regain control. He reminded himself that this was _Jim Moriarty_. A criminal mastermind. He shouldn't give into this, no matter what his hormones told him. No matter how good Jim smelled. Suddenly, Jim dipped down and licked an erect nipple, causing John to gasp and let his eyes flutter shut. Already, his breathing was uneven. Jim's hands slowly shifted down his chest and stomach before pulling at John's belt. Instinctively, John reached down to help only for his hands to fumble and get in the way. Jim quickly shooed him away before pressing a kiss into John's throat. It was enough to make John whine for more. By then, Jim successfully removed the belt and dropped John's pants.

Taking a step back, Jim appraised what was in front of him. John's natural lubrication was already beginning to run down his legs, and his cock jutted out, aching for attention. "Gorgeous," Jim murmured before his eyes landed on the scar. John let out a whine as Jim touched it softly. He didn't like it when people paid too much attention to it, and under Jim's keen eyes, he felt more vulnerable than ever before. "And _mine_."

"Yours," John instinctively said as he finally began to notice just how empty his arse was. The heat was almost fully upon him now. He couldn't stop it… didn't want to even try anymore. "Jim," he whined impulsively, hoping to convey what he needed. Part of him still knew that he shouldn't give in – reminded him who this was – but that voice was being drowned out by the hormones of John's heat. His instincts were starting to take over, forcing him to lose his logic.

Jim's eyes dilated to the sound of his name being cried out. "Shush, Johnny," he soothed, reaching down and grabbing the base of John's cock and giving it a few quick strokes. It was just enough to curb John's need. "I know. I know." He leaned in and kissed up John's neck, his other hand exploring the curves of John's chest before locking firmly on his hips. "Undress me. Carefully. This is a Westwood, after all."

Without hesitating, John reached forward and undid Jim's trousers, pleased to feel even underneath the folds of fabric that Jim was just as hard as John. He let those hit the shower floor before moaning as Jim nipped at his Adam's apple. Shaking, his fingers fumbled with the buttons of Jim's shirt. He swallowed hard as he felt Jim's teeth tug at his neck. And then he felt his dick twitch as he understood that Jim was marking him. More roughly than intended, John pulled off Jim's suit jacket and shirt all at once. Jim dropped his arms in order to let the clothes drop. Once they were on the floor, he kicked them all outside the shower before closing the curtain – as if anyone was going to walk in on them – and turning the shower on.

John yelped as he felt the cold water hit his skin. Jim shushed him, shifting in front of John in order to block the spray. Meanwhile, his hand dropped to John's bollocks. He fondled them gently, making sure to spread them apart and squeeze them just to see how John would react. Whining, John thrust his hips forward before looking Jim in the eyes. He needed to be filled – to be claimed – to be fucked. Without Jim inside of him, John felt like he would lose his mind.

"Jim," he sobbed out, his voice desperate. His heat washed over him, clearing his mind of any coherent thoughts. All he knew was that he needed to be fucked – an Alpha inside of him – knotting him, mating him, claiming him – and that Jim was his only hope.

Without a word, Jim turned him and pushed him forward until John was under the spray of warm water and braced against the wall in front of him. The water ran down his back and sides, wetting his whole body. It wasn't until then that he realised it was also removing anyone else's scent from him. Suddenly, he felt a nip at the back of his neck. He let out a moan of appreciation, glad to still have contact with his Alpha. Jim growled in approval, nipping John's neck yet again. Jim's hands, which had remained on his shoulders after moving him, gradually trailed down John's sides. He reached down and pushed John's inner thighs. Immediately, John complied, spreading his legs out. His breath hitched as he imagined Jim's cock finally sliding inside of him. He needed it so badly, and he let out another whine. The only thing that kept him from trying to impale himself was the feeling of Jim's hands on his thighs.

"Relax, Johnny," Jim ordered quietly, his voice deep and filled with lust.

When John felt Jim's cock drag across his balls, he complied with the order. A hand disappeared for a moment, and John let out a groan of relief when he felt the glans slide into his arse. With every centimetre, John felt the ache dull. Once Jim was fully seated inside of him, John shifted a bit to get used to the feeling. Suddenly, he felt lips pressed against the side of his neck. John bared it submissively, and Jim moaned before sucking on the skin in order to leave another love bite. It was then that John realised it would mirror the first one. Teeth still pulling at the skin, Jim pulled out halfway before sliding back in with ease. John let out a moan as his prostate was struck. If his arms hadn't been bracing his body off the wall, he would have reached back and dug his fingernails into Jim's skin.

As Jim began to slowly thrust in and out of John, he hissed, "To whom do you belong?"

"You!" John moaned out as his prostate was hit again.

"Say my name."

"Jim Moriarty," John cried out, beginning to move with Jim's measured thrusts. He was so far gone in his heat that he didn't care anymore. He just wanted to be claimed – owned in a way that Sherlock couldn't provide. As long as he wasn't mated by an Alpha, he would always have this need. "I'm yours, Jim. I'm only yours." Instantly, Jim's thrusts became faster yet no less smooth. John clawed at the shower tiles as he felt his prostate struck unerringly, and he couldn't hold back his moans. "Oh, fuck, Jim. Yes, that's it. Oh, damn. Just like – nngh – just like that," he cried out encouragingly.

"I'm your Alpha now, Johnny," Jim growled in his ear. John could feel the knot beginning to form, and he groaned at the thought of having it inside him. "I own you. You're now my Omega. Not Sherlock's. Not anyone else's. Do you understand?"

"Yes," John gasped, tossing his head back and closing his eyes as his arse was filled over and over again. "You're my Alpha. I'm your Omega."

Jim began to move erratically, his thrusts sharper and faster than before. With every second, his knot was more defined, and John's cock started becoming painful. He whined out Jim's name. As if Jim knew exactly what John meant, he reached around and began to stroke John. Within seconds, John felt himself on the edge of climax. Without saying a word, Jim shut off the water from the shower and rammed into John, forcing his knot past the sensitive rim. John let out a scream as he finally came, and Jim sank his teeth into John's scar. Pain almost overrode the pleasure of it, and John tried to pull away only for Jim to lock him in place and force his wrist under John's nose and in front of his mouth. Quickly, John's muscles began milking Jim's cock dry, pulling out three shuddering orgasms. Meanwhile, John sucked in large breaths of Jim's scent, imprinting it into his senses as his Alpha. He licked it just to get a taste of his Alpha before Jim pulled it away. Very carefully, Jim licked the bite mark he left on John's previous scar – the one that showed how he became a werewolf in the first place. The lick was affectionate in a way, but John couldn't pay much mind to that as his body began to drain of energy.

"Whoa there, Johnny," Jim chuckled softly as John began to sink forward. He pulled John back and gently kissed his neck again, their bodies still locked together via the knot inside of him.

It was only then that cold reality started to wash over John. He had just bonded with Jim Moriarty – Sherlock Holmes's archenemy. Almost instantly, an icy feeling hit his stomach. Swallowing hard, he tried to figure out what they had just done. What _he_ had just done. His breathing began to quicken, his body rigid despite the post-coital chemicals rushing through his veins.

"Breathe in."

The voice of his Alpha managed to cut through his fear. John instinctively followed the instruction. He _wanted_ to follow his Alpha's orders perfectly – to please his Alpha in any way possible.

"Count to three."

One… two… three…

"And exhale," his Alpha murmured.

He kept listening to the instructions, which actually calmed him, until the knot had deflated enough for Jim's cock to be removed. Once it was out, John gradually turned around to face Jim, still technically in his Alpha's arms. His mind was reeling with what he had just done. All things considered, he shouldn't be as disappointed in himself as he was. It was chemistry, after all, and once an Omega went into heat, everything went from logical to physiological.

Blinking up at Jim, he just shook his head and murmured, "What now?"

"Now…" Jim stalled for a moment, clearly at a loss of what to do himself. So he hadn't planned on being overwhelmed by the heat either. "We have what? An hour before your next heat?"

"Sounds about right," John concurred, shifting uncomfortably.

"Sherlock will be here in ten minutes," Jim said, clearly to himself.

Even so, that didn't stop John from responding. "Sherlock's coming here?"

"Don't look so horrified. He set up the meeting himself. Time and place. I was just planning to use you to taunt him, but now…" Jim's voice trailed as his eyes darkened. Very slightly, his grip on John tightened. Just a touch possessive. Apparently, whatever Jim had planned for John wouldn't work out now. "Now, we tell Sherlock that you're _my_ Omega. He'll get angry and defensive and possessive, but he cannot deny the bond that we've forged."

Almost inaudibly, John murmured, "I don't want to give up my life." He knew that, technically, Jim had every right to take him. By cultural standards, Omegas were the property of their Alphas. In society's eyes, John no longer had any rights of his own. Sherlock would have ignored such power in regards to John, which is one of the reasons they fit each other so perfectly. But Jim could very well abuse the power he held over John. If he wanted, Jim could ensure that John never saw Sherlock again.

"We'll talk about that more once the heat is over, and we can think more clearly than just a few hours at a time," Jim reassured him. John was just thrilled that it sounded like there would be an option. "For now, though, get dressed." As John did so, Jim became very quiet and still. After a long moment, he flipped out his mobile and started to call someone. "Sebby. I have a new mission for you. I need you to meet with Sherlock Holmes instead. Tell him that I have no time for him right now. That once my Omega is no longer in heat, I will." He pursed his lips for a moment. "Yes, I said 'my Omega.' That's not what's important, though. You have your orders. Fulfil them." There was another pause. "Hm… Tell Sherlock that he'll know when my Omega's heat is done. Oh, and tell him to not worry about John Watson too much. He's in good hands." With that, Jim turned off his mobile.

John was dressed by then, and he could feel Jim's cum leaking out of his arse. "So we're…?"

"Going home before you have another heat. Then we can fuck properly. On my bed and everything. Not just any Omega I bond to gets that." The last part was said jokingly, a way for him to break some of the tension.

John offered a small smile in response before swallowing hard. It was an old joke that he had heard before. "Alright," he murmured as Jim started to get dressed.

Once fully clothed, Jim wrapped an arm around John's shoulder, tugging him in close as they headed out of the sports centre. Even though he wasn't sure about his future – There were still many unknowns about Jim Moriarty – he still felt safe, surrounded by the scent that had already become a part of him. He felt as if he was where he belonged.

And, under the circumstances, he couldn't ask for much more.


End file.
